Reinforcing agents are added to polymers to improve the physical, thermal, mechanical, and electrical properties of the matrix. One of the key issues with achieving optimal benefit from the reinforcement is dispersion in the matrix. In dispersive mixing, agglomerates are broken down and the particle size of the dispersed phase is reduced.
Nanoparticles are an attractive reinforcing agent for polymers due to their small size and large surface-to-volume ratio. As well, their small size allows nanoparticles to provide property improvement without imparting directional-dependence. Materials such as clay and nanocrystalline cellulose (NCC) are becoming more commonplace as reinforcements and the market for these reinforcements is expected to grow.
However, nanoparticles suffer from the same issues as other reinforcements with respect to dispersion. Mixing must be sufficient in order for the particles to disperse properly, yet the temperature cannot become too elevated or the particles may degrade.
Cellulose nanocrystal (CNC) hereafter referred to also as nanocrystalline cellulose (NCC), discovered in 1949 by Bengt Ranby, was prepared from acid hydrolysis of naturally existing cellulose semicrystals. It is abundant, renewable and biodegradable, CNC can be used as a building block for the preparation of various functional nano-materials as it possesses a number of advantages, such as low density, high specific surface area, and superior mechanical properties. The numerous hydroxyl groups on the nanocrystal surface can be used to modify CNC.